Thinking Process
Ans. (b)
Sol. There are two stores of nutrients reserve pool and cycling pool.
Ques. If the carbon atoms fixed by producers already have passed through three species, the trophic level of the last species would be
(a) Scavenger (b) Tertiary producer (c) Tertiary consumer (d) Secondary consumer
Ans. (c)
Sol. Producer $\rightarrow \underset{\text { (Primary consumer) }}{\text { Ist Trophic level }} \rightarrow \underset{\text { (Secondary consumer) }}{| \text { Ind Trophic level }} \rightarrow \underset{\text { (Tertiary consumer) }}{\text { IIrr Throphic level }}$
Sol. to be continued
Ques. Which of the following type of ecosystem is expected in an area where evaporation exceeds precipitation, and mean annual rainfall is below $100 \mathrm{~mm}$
(a) Grassland (b) Shrubby forest (c) Desert (d) Mangrove
Sol. In true desert biome rainfall is less than $100 \mathrm{~mm} /$ year, characterised by extremely hot days and cold nights.
Shrubby forest receives rainfall $90-150 \mathrm{~cm} / \mathrm{yr}$.
Mangrove forests receive annual rainfall ranging from $100-150 \mathrm{~cm} / \mathrm{yr}$.
Thus, there options are wrong.
Ques. The zone at the edge of a lake or ocean which is alternatively exposed to air and immersed in water is called
(a) Pelagic zone (b) Benthic zone (c) Lentic zone (d) Littoral zone
Ans. (d)
Sol. The littoral zone is the zone at the edge of a lake or ocean or in aquatic habitat which is alternatively exposed to air, hence, light is also available and immersed in water.
This costal zone is rich producers from surface to bottom, with a large number of brown and red alga attached at the zone.
Different zones is an equatic ecosystem.
Pelagic zone Any zone of water in a sea or lake that is neither close to bottom nor the shore is pelagic zone.
Benthic zone It is the bottom part of the water body (aphotic zone) light is not available here and it is dark.
Microorganisms and benthic organisms are found in this zone.
Lentic zone refers to standing or relatively still water in an equatie ecosystem.
Different zones in an equatic ecosystem
Ques. Edaphic factor refers to
(a) Water (b) Soil (c) Relative humidity (d) Altitude
Sol. Edaphic factor refers to soil like soil texture, background, mineral, its topography and $\mathrm{pH}$ value etc.
Ques. Which of the following is an ecosystem service provided by a natural ecosystem?
(a) Cycling of nutrients (b) Prevention of soil erosion (c) Pollutant absorption and reduction of the threat of global warming (d) All of the above
Sol. A natural ecosystem maintain its biotic and abiotic factors naturally.
(i) Purify air and water
(ii) Migration of droughts and floods
(iii) Nutrient cycling
(iv) Generation of fertile soil
(v) Maintenance of biodiverstity
(vi) Provide storage site for carbon
(vii) Pollinate crops
(viii) Also provides aesthetic, cultural and spiritual valves
Ques. Name an organism found as secondary carnivore in an aquatic ecosystem.
Ans. In an aquatic ecosystem, food chain can be drawn as follows
Ans. to be continued
Ques. What does the base tier of the ecological pyramid represent?
Ans. The base tier of the ecological pyramids represent the producers or first trophic level in case of three ecological pyramids (i) Pyramid of number
(ii) Pyramid of biomass
(iii) Pyramid of energy
Ques. Under what conditions would a particular stage in the process of succession revert back to an earlier stage?
Ans. Natural disturbances like fire, flood or any other natural disaster and anthropogen activities can revert back to an earlier stage of succession.
Ques. Arrange the following as observed in vertical stratification of a forest; Grass, Shrubby plants, Teak, Amaranths.
Ans. Vertical stratification (dispersion) of species in a forest ecosystem is arranged as grass (floor of forest) $\rightarrow$ Amaranthus $\rightarrow$ Shrubby plants $\rightarrow$ Teak (tree).
Ques. Name an omnivore which occurs in both grazing food chain and the decomposer food chain.
Ans. Cockroaches and crow are two omnivore, that are present in both grazing or predator and detritus food chain.
Ques. Justify the pitcher plant as a producer.
Ans. Pitcher plant (Napenthes) is an insectivores plant, which is chlorophyllus and capable of trapping solar radiations for chemical energy for photosynthesis.
Ques. Name any two organisms which can occupy more than one trophic level in an ecosystem.
Ans. Human being (man) and birds (sparrow) can be frequently seen in more than one trophic level, in an ecosystem.
Ques. In the North East region of India, during the process of jhum cultivation, forests are cleared by burning and left for regrowth after a year of cultivation.
Ans. Forests that are cleared by burning and left for regrowth will show secondary succession.
Ques. Climax stage is achieved quickly in secondary succession as compared to primary succession.
Ans. The rate of ecological succession is quicker in secondary succession as compared to primary succession as the soil (substratum) is already available for further succession.
Ques. Among bryophytes, lichens and fern which one is a pioneer species in a xeric succession?
Ans. The species that invade a bare area are called pioneer species.
Ques. What is the ultimate source of energy for the ecosystems?
Ans. Solar radiation is the ultimate source of energy for the ecosystem except deep hydrothermal ecosystem.